Arid Zone Journal of Engineering, Technology and Environment (AZOJETE)
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Cranfield University and University of Maiduguri CubeSat (CUUMcube) for Technology Demonstration: Baseline and Mission Design
Get PDFCubeSats are small satellites that can be deployed to orbit to achieve various space mission goals. Lately, there are several CubeSat launch opportunities from the International Space Station (ISS). For University of Maiduguri to be able to bid for such launch opportunities there is a need for a baseline for a spacecraft and a mission design. Thus, this paper using the Systems Engineering approach is a baseline and mission design for a CubeSat using CubeSat COTS (commercial off-the-shelf) components targeting the KiboCUBE opportunity. CUUMcube mission is a technology demonstration mission to fly two payloads, Cranfield’s Acoustic Sensor and De-Orbit Mechanism (DOM). The Acoustic Sensor is a microphone that measures vibrations, it is intended to measure vibrations due to: spacecraft thermal cycling mechanical noise, antenna deployment, Micrometeoroids and Orbital Debris (MMOD) impacts, DOM deployment and changes in acoustic response of spacecraft after deployment of both mechanisms. The DOM is a deployable drag sail, a passive method of removing spacecraft from orbit afterlife in the effort of mitigating space debris.
Thus, mission baseline reached after the design is to deploy a 1U CubeSat, to carry two payloads (Cranfield’s Acoustic Sensor and DOM), using COTS components. The deployment of the spacecraft will be from the ISS into an elliptical orbit (perigee: 380km, apogee: 420 km).
The ground control stations are COTS component too, where there will be one each in UK and Nigeria. Lastly, 30 mins after deployment into orbit the mission sequence starts from the activation of spacecraft to 24 hours recording mode to monitoring mode by the acoustic sensor to capturing of vibrations. Hence, the antenna and the DOM will be deployed. The DOM will speed the orbit decay of the spacecraft, as a result it will speed the re-entry phase and burn in the process
Assessment of energy potential of municipal solid waste from university of derby student residence
Get PDFSolid waste generated from the University of Derby Student Residence was used to examine the amount of thermal energy that can be reclaimed from the waste. The waste material used for the analysis was categorized into different constituents which were used for analyzing the sample, from which the recoverable energy was estimated. The calorific value of the waste mixture was found to be 34.28 MJ/kg with a corresponding thermal energy recoverable estimated to be 1532.96 MJ/day, which gave an equivalent power of 425.82 kWh/day. The findings from this study suggests the necessity for the adoption of waste management systems that will integrate energy recovery from wastes in order to supplement the increasing demand for energy
Impact of corrosion monitoring techniques on durability assessment in reinforced concrete: A review
Get PDFCorrosion of reinforcement in concrete structures remains a durability issue in structural engineering with the increasing cost of repair and maintenance. The mechanism and factors influencing reinforcement corrosion in concrete with various electrochemical monitoring techniques including non-destructive and destructive techniques have been considered. Also, the roles of sensors have been reviewed to determine the monitoring technique that proved most effective in determining corrosion parameters and more practicable for the assessment of concrete durability. Electrochemical impedance spectroscopy and linear polarization resistance techniques showed great performance in evaluating corrosion kinetics and corrosion rate respectively while gravimetric weight loss technique provided accurate measurements. No single monitoring technique showed to be the ultimate technique, and this calls for more research work in the development of more dynamic monitoring tools capable of considering all possible corrosion factors in the corrosion monitoring process.
 
Assessment of Solar Box Cooker (SBC) with Kapok fiber insulator under Maiduguri Weather Conditions
Get PDFThis paper presents the construction and performance evaluation of solar box cooker with kapok insulator. The solar cooker offers an economically viable alternative while mitigating environment degradation due to excessive use of biomass/conventional energy sources for cooking purposes. The Bureau of Indian Standard (BIS: IS B429) was used to determine the thermal performance parameters of the cooker, where first figure of merit (F1) and second figure of merit (F2) were determined to be F1= 0.132 and F2= 0.58. The cooker thermal efficiency (η) = 44%, qualifying the cooker to be grade “A” according to BIS. The American Society of Agricultural and Biological Engineers for Solar Cooking (ASAE S580.1) was used to determine the cookers cooking power and it was found to be (Ps) =14.7W while the (R2) value was 0.137 coefficient of regression
Effect of elevated temperature on the durability and strength properties of concrete with ground rice husk ash as a partial replacement to cement: a review
Get PDFConcrete is a construction material composed of cement, fine aggregates (sand) and coarse aggregates mixed with water which hardens with time. Cement is an important constituent in the concrete composite; however, its cost is relatively very high, this has impacted in the cost of concrete production and by extension on the cost of housing delivery in Nigeria. Rice husk ash is one of the promising pozzolanic materials that can be blended with Portland cement for the production of durable concrete and at the same time a value-added product. the use of the rice husk ash as partial replacement to cement in concrete not only improve the strength of concrete, protection against cracking, spalling, reduce density and porosity of the concrete. It also reduce the emission of carbon monoxide to the environment which is very dangerous to the atmosphere. The elevated temperature is one of the most harmful effects that cause durability problems in construction; this effect can cause permanent damage in construction and reduce the service life. This paper reviews the work presented by various researchers on effect of elevated temperature on the durability and strength properties of concrete using rice husk ash as partial replacement. From the available literature reviewed, there is a possible research gab in investigating the effect of elevated temperature on concrete with rice husk ash as partial replacement to cement, because most of the researchers have focused on conventional concrete, whereas concrete with rice husk ash as replacement to cement have been recommended for use with a replacement value of 10-20%. The degree of its performance of these recommended replacement needs to be investigated
Solid Waste Generation and Characterization in Ilorin, Nigeria
Get PDFGlobal per capita waste generation rates and characterization vary by regions, countries, and within cities. The generation, l and characterization of waste from selected areas in Ilorin, Nigeria, prone to indiscriminate disposal of solid waste without consequence were analyzed for proper management. Municipal solid wastes were sorted, analyzed by weight and percentage composition using the quantitative approach. The average generated waste per capita was estimated to be 0.66 kg/day, w/w distribution was 57.53% food waste, 9.07% nylon (flexible films), 5.98% plastic (rigid containers),4.95% textile, 10.51% paper and 11.96% others. The average moisture content was 46.16% food waste, 20.63% nylon, 18.65% plastic, 36.67% textile, 18.45% paper and 42.89% others. The results show an average bulk density of 10.36 Kg/m3 of food waste, 2.14 of nylon, 0.5 of plastic; 0.93 of textile; 2.74 of paper and others 5.36. The chemical analysis showed that volatile matter ranged from 20.55 to 24.10%, ash content 3.10to 3.90%, fixed carbon 7.5to 9.8%, calorific value 14820to 18360 (kJ/kg), nitrogen 0.40to 0.50%, hydrogen 4.38to 5.80%, carbon 40.90 to 44.30%, oxygen 30.80 to 34.60%, Sulphur 0.19 to 0.24%, fusing point of ash 3.12to 4.38 °C, and heating value from 13.520to 13.64 KJ/Kg. The results generated could play a positive role in the management of solid waste in that area.
 
Comparison of square and circular isolated pad foundations in cohesionless soils
Get PDFOne of the most commonly used pad foundation types is the square footing, however, there is a necessity to compare its performance and economy with the circular pad foundation which is not often considered. This study focuses on the suitability of the square versus circular isolated pad foundation types in cohesionless soils, from a geotechnical, structural, and construction cost perspective. The square and circular pad foundation types were subjected to three (3) cases, which were: when the foundation footings have equal width or diameter (Case 1), when the foundation footings have an equal axial load capacity (Case 2), and when the foundation footings are restricted to a defined net allowable bearing capacity (Case 3). The factors evaluated in each of these cases were bearing capacity, immediate settlement, structural design, and construction cost. Additionally, a model for estimating the construction cost of reinforced concrete was proposed in this study, and it was used to estimate the construction cost of the reinforced concrete isolated pad foundation types. The results of this research work show that overall, the square isolated pad foundation type will be the better selection for most design and construction considerations
Influence of energy recovery system on the energy efficiency of a flat-bed dryer in the drying of turmeric
Get PDFDrying is one of the most energy intensive unit operations in agricultural and food processing industry. Energy costs represent a major fraction of cost of operation of a mechanical dryer, therefore, the more efficient a dryer uses its energy supply, the lesser its cost of operation and the better it impacts on profitability of drying process. A flat-bed dryer of 25kg capacity was developed and fitted with air-to-air indirect mixing heat exchanger (Heat Recovery Unit, HRU) at the vent of the drying chamber. The dryer was tested to determine the impact of exhaust vent waste heat recovery on its energy efficiency and cost of operation. Turmeric, an important spice crop was dried at three temperatures of 60°C, 65°C, and 70°C under two operating conditions; (i) without HRU (C-I) and (ii) with HRU (C-II). The result show thermal efficiency, at C-I it was found to be 28%, 27% and 27% at 60°C, 65°C and 70°C respectively and for C-II it was 42%, 42%, and 40% at 60°C, 65°C, and 70°C respectively. This indicates that the overall thermal efficiency was improved by 15% for C-II at 65°C as compared to C-I at 65°C. ANOVA show there is significant different (P< 0.05) between C-II and C-I as regards thermal efficiency. The result also showed that specific energy consumption was reduced for all drying temperatures levels of C-II as compared to C-I and the result shows that testing condition C-II, at 65°C has the lowest specific energy consumption of 1.79(kWh/kg) while C-I at 60°C has the highest value; 2.37 (kWh/kg), this showed significant different (P< 0.05).Drying curves of turmeric were plotted and it was found that C-II performed better in drying turmeric since the moisture lose was faster than in C-I and the drying time was lowered by 4hrs for C-II at 65°C compared to C-I 65°C. The average Return on Investment (ROI) of HRU was calculated considering average of 260 working days or 130 batch drying operation per annum with one drying cycle per two working days and was found to be 0.61 and the payback period was 19 months. It was concluded that the developed flatbed dryer can be used to dry 25 kg of turmeric per batch in 25 hours drying time using operating condition C-II, 65°C which showed better quality in terms of energy efficiency and drying rate.
 
Strength properties and microstructural characterization of metakaolin geopolymer concrete synthsized at ambient temperature.
Get PDFGeopolymer concrete has been gaining extensive attention in recent years due to its numerous advantages over Ordinary Portland cement concrete in terms of reduced carbon footprint, improved mechanical strength, durability as well as chemical resistance. However, production of geopolymer concrete is usually affected by several factors such as the synthesis temperature, nature of the source material and the type of alkaline activator used. For these materials to have wider application within the Nigerian construction industry, there is a need to synthesize the concrete at ambient temperature and to examine the suitability of native Alkaleri kaolin to produce geopolymer concrete. The study presents the strength and microstructural properties of Metakaolin Geopolymer Concrete synthesized at ambient temperature. Alkaleri calcined kaolin from Bauchi state Nigeria was used as the main geopolymer precursor with sodium hydroxide and sodium silicate as the alkaline activating agent. The Geopolymer concrete was prepared with Silicon/Aluminium ratio of 2.0 and 2.5 (Geopolymer concrete M1 and M2 respectively) and cured for 3, 7, 14, 28, and 90 days at ambient condition (average temperature of 26°C and average relative humidity of 61± 15%). Fourier Transform Infra-Red, X-ray Diffraction, Thermo-Gravimetric Analysis, Scanning Electron Microscopy as well as compressive strength and split tensile strength test were conducted on the Geopolymer concrete at appropriate curing age to examine their microstructure and strength properties. The Fourier Transform Infra-Red revealed that there was an immediate geopolymeric reaction between the metakaolin and the alkali activator. The X-ray Diffraction showed that the raw metakaolin sample and both Geopolymer concrete M1 and M2 were amorphous in nature; while the Geopolymer concrete M2 (Silicon/Aluminium ratio of 2.5) exhibited good dissolution of the kaolinite which resulted in a more compact and stable structure in comparison with Geopolymer concrete M1 (Silicon/Aluminium ratio of 2.0). This was also confirmed by the Scanning Electron Microscopic images of the Geopolymer concretes. The Thermo-Gravimetric Analysis revealed that both Geopolymer concrete M1 and M2 were thermally stable at 300°C and at 800°C, only the organic phase of the geopolymer decomposed. The strength properties (compressive and tensile strength) of Geopolymer concrete M1 and M2 increased with increase in the curing age, and Geopolymer concrete M2 displayed slightly higher strength in all the curing ages as compared with the Geopolymer concrete M1. This implies that the higher the Silicon/Aluminium ratio, the higher the mechanical strength of the geopolymer. Both the Geopolymer concrete samples attained a compressive strength that can be acceptable for structural use as normal strength concrete grade C20/25 as specified in the requirement of BS EN 206-1 2000 at 28 days curing
An Experimental Study on the Performance of Bituminous Concrete Mixtures with Silica Sand as Filler Replacement
Get PDFThis study investigates the performance of silica sand as a partial replacement for cement filler in bituminous concrete mixtures. The physical properties of bituminous concrete mixture constituent materials were tested in accordance with American Society for Testing and Materials ASTM and British standard BS specifications and were found to be satisfactory. Marshall stability method of bituminous concrete mix design was adopted to determine the optimum binder content at no silica sand replacement (control) within the bitumen content range prescribed by Nigerian General Specifications for Roads and Bridges and Asphalt Institute for bituminous courses in flexible pavements and an optimum binder content (OBC) of 6% was obtained. The Marshall stability-flow and void-density analysis of bituminous concrete mixtures prepared with 6% OBC at varying percentages replacement (5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, and 45%) of silica sand was conducted to obtain the mixture with the best performance in terms of strength and waste utilization. The results obtained from the experiment shows that the replacement of cement filler with silica sand up to 45% meets the standard specifications of Nigerian General Specifications for Road and Bridges, Hence, silica sand up to 45% could be partially adapted as cement filler replacement in bituminous concrete mixes.